Conventionally, liquid crystal display devices have been used in various fields, and are used especially often in the electronics industry such as in personal computers and televisions. Liquid crystal display devices that employ a direct-type backlight system have backlights arranged on the rear surface of the liquid crystal panel, while those that employ an edge-type configuration direct light emitted from a light source into a light guide panel and emit the transported light from the front surface of the light guide panel through a prism sheet or the like, thereby illuminating the entire rear surface of the liquid crystal panel.
The light sources of backlights often consist of small fluorescent tubes known as CCFL's (Cold Cathode Fluorescent Lamp) or LED's (Light Emitting Diode). However, in recent years, concern for the environment has led to wider usage of backlights having LED light sources instead of CCFL's, which contain mercury.
Additionally, there is a demand to make liquid crystal display devices for televisions larger, and this requires large quantities of light. Therefore, there is a need to supply as much light as possible to the liquid crystal portions. In order to thus maximize the amount of light supplied from backlights, it is necessary to make effective use not only of the light emitted from LED's, but also of reflected light. The use of light reflecting sheets is common as a means for making effective use of such reflected light (see Patent Document 1). Conventionally, the printed circuit boards for mounting the LED packages used in direct backlights have not had a function of reflecting light, and so light reflecting sheets were applied to the printed circuit boards after mounting LED packages in order to use them in backlights.